1. Field of the Invention
The invention relates to a method and apparatus for heating a fluid, which, in turn, is used to heat an apparatus such as an injection mold.
2. Description of Background Information
The heating of equipment such as plastic injection molds, is often accomplished by use of a heat exchange fluid. This heat exchange fluid, in turn, is heated by means of a heat supply unit. The heat supply unit is generally positioned, for example, on the sides of a press adapted to be equipped with the molds. The manufacture of these heat supply units requires a number of very expensive elements which are cumbersome and delicate and, therefore, must be installed very carefully.
The essential elements of such heat supply units comprise:
(a) a heat exchanger in which heat is transferred to the fluid; PA1 (b) a pump for propelling the heated fluid toward an apparatus to be heated by the fluid, hereinafter referred to as a utilization or heat consumption circuit. The pump also returns the heated fluid to the heat exchanger after the fluid gives up its heat to the heat consumption circuit; and PA1 (c) a feed reservoir; this reservoir is needed to store fluid which is not utilized in the heat consumption circuit itself and which must be available to fill the circuit if necessary, particularly when molds of different capacities are interchanged with each other. PA1 (a) a variety of separate components is used; PA1 (b) laborers having various specialties for the assembly of the unit (e.g., welding, brazing, pipe fitters, insulation, adjustment, etc.) must be used; PA1 (c) the installation of the unit is time consuming and costly because the units are very large so as to compensate for the low efficiency of heat exchangers presently on the market; further the heat exchangers currently available have an energy loss which is proportional to the total surface of the consumption circuit and are difficult to adjust the temperature of as a result of the large heat inertia of the unit; PA1 (d) the circulation pump has a low efficiency as a result of the length of the pump exhaust pipes; and PA1 (e) the installation of insulation which must be provided after assembly of each of the various elements is complex.
Even when the heat supply unit is reduced to its essentials components allowing for the storage, the heating and the circulation of the fluid, the present state of the art requires that the heat supply unit be composed of distinct elements which are connected to one another and mounted in a factory so as to provide the user with a functional unit adapted to be connected to the heat consumption or utilization circuit.
The manufacture of these prior art heat supply units suffers from the following disadvantages:
Applicant has solved some of these problems by integrating the heat exchanger and the circulation pump into a single unit in U.S. Pat. No. 4,232,733. However, that unit does not contain a reservoir for storing fluid, and therefore, the heat exchanger of this patent cannot be adapted to molds of different capacities.
Thus, there is a need for an improved heat supply unit does not suffer the disadvantages discussed above.